Locking device for electric light bulbs



April 5, 1938. I c HEALEY 2,113,138

LOCKING DEVICE FOR ELECTRIC LIGHT BULBS Filed June 1, 1936 Patented Apr. 5, 1938 UNITED STATES PATENT OFFICE LOCKING DEVICE FOR ELECTRIC LIGHT BULBS This invention relates to a device for preventing the unauthorized removal of electric light bulbs from sockets in which they are inserted.

It is an object of the invention to provide a 5 device such that the socket element, into which the lamp base is screwed, will normally turn freely with the bulb so as to prevent the unscrewing of the light bulb therefrom. According to the invention, a clutch device is pro- 10 vided by which the socket element can be temporarily held against rotation for the insertion or removal of an electric light-bulb, a special kind of electromagnet being required for the operation of such clutch device.

15 For a more complete understanding of the invention, reference may be had to the disclosure of certain embodiments thereof in the following description and on the drawing of which- Figure 1 is a perspective view of the several parts of a device embodying the invention.

Figure 2 is a longitudinal sectional view of the same.

Figure 3 is a sectional view of a portion of the device shown in Figure 2, the parts being shown 25 in a different position of operation.

Figure 4 is a section on the line 44 of Figure 2.

Figure 5 is a section on the line J5 of Figure 3.

30 Figure 6 is a fragmentary sectional view showing a modified detail.

Figure 7 is a sectional view of a modified form. of the invention.

The invention may be embodied in an adapter 35 capable of being inserted in an ordinary outlet adapted to receive an electric light bulb, as illustrated in Figure 2, or may be embodied in a fixture, an example of which is illustrated in Figure 7. In either case, the invention includes 40 a support to which an electric light socket is permanently but rotatably attached, and clutch means by which the socket can be temporarily locked against rotation relative to its support. In Figure 2 is illustrated an adapter consisting 45 of a support in the form of a plug element I ll and a socket element I2 permanently attached thereto, the latter being adapted to receive the base of a conventional electric light bulb I4. The plug portion I is provided with a threaded shell 50 I6 adapted to screw into a conventional socket 20 having a central contact member 22. The plug element Ill and.the socket element I2 may be secured together for free relative rotation as by a central rod 24 which has a head 26 at one 5 end and is peened at the other end as at 28 over a washer 30 which bears on an insulating disk 3I. The rod 24 extends through a tube or jacket 32 of insulating material and is preferably freely rotatable therein. Between the plug element III and the socket element I2 is a clutch device 5 comprising two metal blocks 34 and 36 which have square transverse cross sections of the same size. Each of these blocks is provided with a central bore 40 through which pass the rod 24 and the insulating tube 32. Surrounding the tube 32 within the bores 40 is a spring 42, one end of which presses against a metal plate 44 mounted on one end of the plug element II), the other end of the spring 42 bearing against a metal plate 46 which is secured to the base of the socket shell I2. The plate 44 is electrically connected as by a wire 48 to the shell I6'of the plug element I0, the connection between the wire 48 and the shell I6 being made by a metal element such as a drop of solder 50 which projects radially beyond the shell I6, so that, when the adapter is screwed into the socket 20, the projecting portion of the element 50 comes into binding engagement with the edge of the shell in the socket so that the plug element I0 is thus frictionally held against rotation which might tend to unscrew it from the socket 20, this frictional binding engagement occurring before the plug element I3 has penetrated the socket far enough to press the resilient contact element 22 in against the bottom of the socket. This leaves the head 26 of the rod 24 in suificient contact with the element 22 for good transmission of current but leaves the rod 24 to turn freely without binding engagement against the element 22..

The plates 44 and 46 are centrally depressed as at 52 to receive the remote end faces of the blocks 34 and 36. Thus the block 34 is held against rotation relative to the plug element III while the block 36 is held against rotation relative to the socket element I2. As long as these two blocks are relatively rotatable with respect to each other, the socket element I2 can be freely rotated relative to the plug element ID. This is the normal condition of the adapter, as illustrated in Figure 2. Thus, if a bulb I4 is engaged in the socket I2, any effort to rotate the bulb I4 will result in rotation of the socket element I2 and the block 36. In order to hold the socket element I2 against rotation for the removal or insertion of a bulb, the blocks 34 and 36 may be temporarily held together by means of a clutch element 56 which, as shown in Figure 1, may consist of a disk having a square central aperture 55 66 adapted to receive the block 54 or 36, and a pair of parallel ears 66 at opposite sides of the aperture 66, these cars being ,adapted to fit against opposite side faces of the block 36 as indicated in Figure 2. The clutch member 56 is normally held in the position shown in Figure 2 by a light compression spring 62, one end of which is preferably secured to the member 66. If preferred, suitable tension springs 63 may be employed as illustrated in Figure 6. Whenever the clutch member 56 is moved toward theleft so that the ears 60 simultaneously engage portions of the blocks 34 and 36, the blocks are held against relative rotation. Since the plug element I0 is normally bound frictionally within the socket 20, the socket I2 is thus held against rotation permitting the insertion or removal of an electric light bulb ll. If desired, the distance of movement of the clutch member 56 toward the left may be limited by the provision of a pair of stops 64 to make difficult the operation of the device otherwise than by the use of a suitable magnet. A suitable tubular casing member 66- surrounds the adapter so as to prevent access thereto. In order to shift the clutch member 56, it ispreferably made of magnetic material, such as iron, so that, if the poles III of a strong magnet are suitably positioned at opposite sides of the casing 66, the magnetic flux will pull the clutch member 56 to the left to the position shown in Figure 3. If at the time the magnet is put into operation, the blocks 34 and 36 are not registering, as illustrated in Figure 4, a slight rotation of the bulb II will bring the block 36 into registry with the block 34, whereupon the flux of the magnet will draw the clutch member 56 to the left so as to lock the blocks together. The casing 66 is preferably made of suitable nonmagnetic material, such as copper or a moldable plastic. This casing extends suillciently beyond the end of the socket shell II to prevent movement thereof toward the right sufficient to expose the adapter. The casing is normally mounted on the end of the socket member 20, being threaded thereon as at 12 on the threaded portion usually provided on a socket shell for the support of a shade or the like. The opposite end of the casing 66 may be threaded as at 14 for the support of a shade.

Figure '7 shows a clutch mechanism similar to that illustrated in Figure 2, but mounted in a structure which is a fixture rather than an adapter to be screwed into the conventional socket. As therein shown, the support to which the socket is rotatably secured is a fixed base 60 of suitable insulating material, this base be ing secured to a wall 82 as bysuitable screws 64. The plate 44 is mounted on the end of this base. A binding screw 86 is electrically connected to the shell I! by a wire 68 which leads from the plate 44, the latter being electrically connected to the shell I2 as hereinbefore described. The head 26 of the rod 24 is electrically connected to a binding post 90 by any suitable means such as a wire or metal strip 92. A casing SM is permanently secured by any suitable means to the base 60, this casing being of non-magnetic material.

It is evident that various modifications and changes may be made in the embodiments of the invention herein shown and described without departing from the spirit or scope of the invention as defined in the following claims.

I claim:

1. A device of the class described, comprising a support, a socket for an electric light bulb rotatably mounted on said support, clutch means operable by a magnet against a restoring force to hold said socket against rotation relative to said support, and a non-magnetic casing enclosing said clutch means.

2. A device of the class described, comprising a support, a socket for-an electric light bulb rotatably mounted on said support, clutch means operable by a magnet against a restoring force to hold said socket against rotation relative to said support, and a non-magnetic casing surrounding said clutch means and socket to prevent access thereto when a light bulb is in place in the socket.

3. A device of the class described, comprising a socket adapted to receive the base of an electric light bulb, a support for said socket, means connecting said socket to said support and normally permitting free rotation of the socket relative to the support, clutch means magnetically operable to secure said socket and support temporarily against relative rotation and a nonmagnetic casing enclosing said clutch means.

4. A device of the class described, comprising a support, a socket for an electric light bulb rotatably mounted on said support, and magnetically operable clutch means for holdingsaid socket against rotation relative to said support, said clutch means including an element of magnetic material non-rotatable relatively to said socket but axially movable into locking engagement with said support, spring means normally holding said element out of engagement with said support, and a non-magnetic casing surrounding said clutch means and socket to prevent access thereto when a light bulb is in position in the socket.

5. A device of the class described, comprising a support, a socket for an electric light bulb mounted on said support and normally rotatable thereon, said socket including a threaded cylindrical shell adapted to receive the base of a light bulb and a central terminal normally engaged by the tip of the base of the light bulb, a pair of electric terminals on said support by which the device may be connected into an electric circuit, means holding said socket on said support and comprising a central rod extending from said central terminal in the socket to one of the terminals on the support and electrically connecting these terminals, means including a spring surrounding a portion of said rod electrically connecting said socket shell with the other terminal on said support, means insulating said rod from said spring and socket shell, clutch means magnetically operable to hold said socket against rotation relative to said support, and a non-magnetic casing enclosing said clutch means.

6. A device of the class described, comprising a plug portion adapted to be screwed into a conventional socket for an electric light, a socket portion normally rotatable relatively to said plug portion, means connecting said plug and socket portions together, clutch means permanently and rotatably magnetically .operable to hold said socket portion against rotation relative to said plug portion, and a non-magnetic casing surrounding said cluteh means and socket portion to prevent access thereto.

7. A device of the class described, comprising a plug portion adapted to be screwed into a conventional socket for an electric light, a socket portion normally rotatable relatively to said plug portion, means permanently and rotatably connecting said plug and socket portions together,

ally movable clutch element of magnetic mateclutch means magnetically operable to hold said socket portion against rotation relative to said plug portion, a lateral projection on said plug portion adapted to engage the edge of a socket into which the device is screwed to limit the penetration of said plug portion into the socket, and a non-magnetic casing enclosing said clutch means.

8. A device of the class described, comprising a plug portion adapted to be screwed into a conventional electric light socket, a socket portion rotatably connected to said plug portion, an axirial normally rotatable with one said member relatively to the other said member, said clutch element having a portion adapted to engage said other member when said element is axially shifted from its normal inactive position whereby said members are temporarily locked together against relative rotation, and spring means yieldingly pressing said clutch element to its normal inactive position.

, HERBERT C. HEALEY. 

